Accumulation of static charges on a photographic light-sensitive material has been a serious problem. Such static charges are generated by handling photographic light-sensitive material during production and use, e.g., when winding a roll, rewinding, conveying with a roller, and by contact with other things when conveying. The mechanism of generation of such static charges and the accumulated state of the charges depends on factors such as the conductivity of the particular photographic light-sensitive material. Factors which affect static charge characteristics include the position thereof in the charging series, the water content therein, the nature of materials cioming into contact therewith and the atmosphere under which the photographic material is placed. The accumulated charges are occasionally discharged and cause irregular fog.
In certain circumstances, the creation of static charges causes a fatal defect in a photographic light-sensitive material depriving the photographic light-sensitive material of its value. For instance, if only a slight amount of fog is generated in a medical Roentgen film due to the above-described phenomenon, it makes it entirely impossible to achieve its desired end. Furthermore, it can lead to a wrong diagnosis.
Providing a photographic light-sensitive material with an antistatic layer in order to aid in the elimination of these undesirable influences due to accumulation of static charges is well known. Namely, a conductive layer provided in a photographic light-sensitive material causes static charges to be scattered and lost. Accordingly, negative influences of static charges on the photographic material are evaded. For this purpose, a number of materials have been proposed. For example, U.S. Pat. Nos. 2,649,374; 3,033,679; 3,437,487; 3,525,621; 3,630,740 and 3,681,070 disclose various kinds of antistatic agents, antistatic layers containing such agents, and so on.
However, the use of such agents and layers have their respective serious defects as a constituent element of a photographic light-sensitive material. For example, an antistatic layer cannot prevent discharge fog from occurring in a highly sensitive photographic light-sensitive material. In another case, an antistatic agent incorporated in an antistatic layer undergoes diffusion into its adjacent layers and exerts adverse effects (e.g., increase in fog, decrease in sensitivity, etc.) upon photographic properties. In still another case, an antistatic layer undergoes elution into a development-processing solution creating scum in the solution. In a further case, an antistatic layer itself tends to get scratches and has low durability, or the film strength of a photographic light-sensitive material is lowered by the presence of an antistatic layer. Accordingly, the finished material is subject to being scratched and its durability is lowered. This results in loss of value as a commodity or the occurrence of difficulties during manufacturing.
In order to eliminate the above-described defects, British Pat. No. 1,496,027 proposes an antistatic layer which contains (a) an anionic macromolecular electrolyte of a water-soluble film-forming polymer having a free acid form (e.g., polystyrenesulfonic acid), (b) a binder of a film-forming, water-soluble, cross-linkable polymer (e.g., polyvinyl alcohol) and (c) a cross-linking agent for the above-described binder polymer (e.g., glyoxal).
However, in the above-described patent the water-soluble anionic macromolecular electrolyte is fixed in a network formed by the binder and the cross-linking agent. Therefore, elution of the water-soluble, conductive, anionic macromolecular electrolyte upon development-processing occurs to some extent. Accordingly, the lowering of pH and generation of scum in the development-processing bath cannot be evaded. In addition, the content of the anionic macromolecular electrolyte in the antistatic layer is about 1/3 to 1/2 of the total weight of the antistatic layer. More specifically, a component not entering the cross-linking occupies 1/3 to 1/2 the weight of the whole components of the antistatic layer. This results in insufficiency of the physical strength of the layer, which is a serious problem to be overcome in the manufacturing of a photographic light-sensitive material, especially in high speed manufacturing.
In order to remedy the above-described disadvantage, U.S. Pat. No. 4,268,623 proposes an antistatic layer containing (a) gelatin, (b) a carboxylic acid group-containing, film-forming, water-soluble polymer and (c) a carboxylic acid-activated type of condensing agent.
However, in some cases, the effect intended by the above-described patent cannot be fully exhibited because the cross-linking reaction among gelatin, an antistatic agent (carboxylic acid polymer) and a carboxylic acid-activated type of condensing agent is affected by manufacturing conditions or preserving conditions.